Structural, microstructural, electrical, and magnetic properties of (FexNiy)100−zCoz ternary films

This work is devoted to the study of the structural, microstructural, electrical, and magnetic properties of (Fe x Ni y ) 100− z Co z ternary thin films, produced from the coevaporation of iron, nickel, and cobalt elements, on monocrystalline Si(100) silicon substrates. We focus on the impact of Co content, the proportions of Fe and Ni being constant ( x / y ~ 0.22). Energy-Dispersive X-ray (EDX) analysis and Rutherford Backscattering Spectra (RBS) tools have been used to quantify the films. We used X-ray diffraction (XRD) and Atomic Force Microscopy (AFM) techniques to investigate the structural properties of the samples. These latter are polycrystalline and grow with the texture. Crystallite sizes are ranging from 17 to 37 nm. The value of the lattice parameter a decreases from 3.539 Å for (Fe 17 Ni 83 ) 82 Co 18 film to 3.524 Å for (Fe 17 Ni 83 ) 62 Co 38 film, when the atomic percentage of cobalt increases. The films are very smooth, the root-mean square being confined in 0.7–2.4 nm range. Electrical resistivity values greater than 33 µΩ cm have been measured for all the films. Hysteresis loops, recorded using a vibrating sample magnetometer, infer that all samples are magnetically soft and characterized by a planar anisotropy, without any preferential direction. The smallest value of the coercive field is equal to 3.4 Oe, the highest value being equal to 30 Oe for the lowest value of Co content. We found that the addition of cobalt to Fe x Ni y alloy ( x / y ~ 0.22) improves its saturation magnetization M s which shows a linear dependence on the atomic percentage z of cobalt. The greatest M s value, obtained for z = 54%, is as high as 17.5 kG, and the smallest one being 15.5 kG, obtained for z = 9%.